1. Field of the Invention
This invention relates to synergistic biocidal combinations including an isothiazolone and one or more of many commercial biocides for more effective and broader control of micro-organisms in various industrial systems. In particular, the present invention relates to the use of a mixture of 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one (also known as 5-chloro-2-methyl-3-isothiazolone, respectively) and 2-methyl-3-isothiazolone, with one or more of the following 14 compounds: Hexahydro-1,3,5-triethyl-5-triazine; 5-bromo-5-nitro-1,3-dioxane; 2-(hydroxymethyl)aminoethanol; 2-(hydroxymethyl)amino-2-methylpropanol; .alpha.-benzoyl-.alpha.-chloroformaldoxime; benzylbromoacetate; p-chloro-m-xylenol; bis-(2-hydroxy-5-chlorophenyl)sulfide; p-tolyldiiodomethylsulfone; 3-iodo-2-propynylbutylcarbamate; bis-(2-hydroxy-5-chlorophenyl)methylene; dipropylamine ether; dodecylamine; and 1-(3-chloroallyl)-3,5,7-triaza-1-azoniaadamantane chloride.
2. Prior Art
The isothiazolones are described in U.S. Pat. Nos. 3,761,488; 4,105,431; 4,252,694; 4,265,899 and 4,279,762. An excellent antimicrobial agent is a mixture of 75% 5-chloro-2-methyl-4-isothiazolin-3-one and 25% 2-methyl-4-isothiazolin-3-one, which is very effective against bacteria, fungi, and algae. The suggested dosages, sometimes, cannot achieve the best results for the control of microorganisms due to interfering nucleophiles, or due to less sensitive organisms in certain systems. To control the situations like these will need higher concentration of active ingredient which becomes more costly in the treatment. Therefore, the search for more effective and broader control methods to achieve the best results has continued.
Many other broad classes of biocidal agents are known. They are commercially available for the control of microorganisms in certain sections of various industrial systems such as paints, wood, textile, paper, pulp, leather, fur, tobacco, rope, plastics, fuel, oil, cosmetics, rubber, adhesives, latex emulsions, joint cements, water treatment, laundry, and metalworking industries, and the like. In general, high dosage requirements make them disadvantageous because of high treatment cost and interference with the formulation of finished product or the operation of the system. Sometimes many biocides cannot provide satisfactory performances even at high use concentrations due to weak activity against certain bacteria or fungi. Without effective control, loss of product, inferior product, production-time loss, health hazard, and other types of problems may occur in the systems.
It has been discovered that combinations of a mixture of 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one with one or more of the 14 compounds within a specified range of ratios results in synergistic biocidal activities against a wide range of microorganisms. The synergy in which the disruptive interaction on the organisms by the two compounds together is greater than the sum of both compounds taken alone does not arise from the expected activity of the components or from the expected improvement in activity. The synergistic combinations provide more effective and broader control of microorganisms in a number of industrial systems.
It is the principal object of this invention to provide the use of synergistic compositions which overcome the disadvantages of the prior art biocidal compositions.
Important applications of the synergistic antimicrobial compositions of the present invention include but are not limited to: inhibiting the growth of bacteria and fungi in aqueous and organic paints, adhesives, latex emulsions, and joint cements; preserving wood; preserving cutting fluids, controlling slime-producing bacteria and fungi in pulp and papermills and cooling towers; as a spray or dip treatment for textiles and leather to prevent mold growth; protecting paint films, especially exterior paints from attack by fungi which occurs during weathering of the paint film; protecting processing equipment from slime deposits during manufacture of cane and beet sugar; preventing microorganism buildup and deposits in air washer or scrubber systems and in industrial fresh water supply systems; controlling micro-organisms contamination and deposits in oil field drilling fluids and muds, and in secondary petroleum recovery processes; preventing bacterial and fungal growth in paper coating processes; controlling bacterial and fungal growth and deposits during the manufacture of various specialty boards, e.g., cardboard and particle board; preventing sap stain discoloration on freshly cut wood of various kinds; controlling bacterial fungal growth in clay and pigment slurries of various types; as a hard surface disinfectant to prevent growth of bacteria and fungi on walls, floors, etc.; in swimming pools to prevent algae growth; inhibiting the growth of harmful bacteria, yeasts, fungi on plants, trees, fruits, seeds, or soil; protecting animal dip compositions against the buildup of microorganisms, and in photoprocessing to prevent buildup of microorganisms, and the like.
The synergistic compositions of this invention may be added separately to an industrial system or may be formulated as a simple mixture comprising its essential ingredients, or together with a suitable carrier or solvent, or as an aqueous emulsion or dispersion.